Patent EP1486827A2 successfully refreshed from Google Patents.
EP1486827A2
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Lithographic apparatus and device manufacturing method
Assignee: ASML Netherlands BV
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Filing: 2004-06-04
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Granted: —
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Expires: 2024-06-04
Abstract
Abstract A lithographic apparatus and device manufacturing method makes use of a high refractive index liquid confined in a reservoir 13 at least partly filling the imaging field between the final element of the projection lens and the substrate. Bubbles forming in the liquid from dissolved atmospheric gases or from out-gassing from apparatus elements exposed to the liquid are detected and removed so that they do not interfere with exposure and lead to printing defects on the substrate. Detection can be carried out by measuring the frequency dependence of ultrasonic attenuation in the liquid and bubble removal can be implemented by degassing and pressurizing the liquid, isolating the liquid from the atmosphere, using liquids of low surface tension, providing a continuous flow of liquid through the imaging field, and phase shifting ultrasonic standing-wave node patterns. <IMAGE>
Inventors
- 👤 Joannes Theodoor De Smit
- 👤 Vadim Banine
- 👤 Theodorus Hubertus Josephus Bisschops
- 👤 Theodorus Marinus Modderman
- 👤 Marcel Mathijs Theodore Marie Dierichs
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 22:20
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/20; G03F7/70; G03F7/70216; G03F7/70341; G03F7/708; G03F7/70858
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
115 words
A lithographic projection apparatus comprising: an illumination system arranged to provide a radiation beam; a support structure configured to support a patterning device, the patterning device
being capable of imparting the radiation beam with a pattern in its cross-section,
thus providing a patterned radiation beam; a substrate table configured to hold a substrate; a projection system arranged to project the patterned radiation beam onto a target
portion of the substrate; a liquid supply system configured to at least partly fill a space between a final
element of said projection system and said substrate with liquid, characterized in that said liquid supply system comprises bubble reduction means and said bubble
reduction means comprise bubble detection means.
Claim 2
Dependent Claim
43 words
A lithographic projection apparatus according to claim 1, wherein said bubble
detection means comprise at least one ultrasonic transducer, the attenuation of ultrasonic
waves in said liquid being measured by said transducer so as to obtain information about
bubbles present in said liquid.
Claim 3
Dependent Claim
20 words
A lithographic projection apparatus according to claim 2 wherein said ultrasonic
transducer measures ultrasonic attenuation as a function of frequency.
Claim 4
Dependent Claim
22 words
A lithographic projection apparatus according to any one of claims 1 to 3, wherein
said bubble reduction means comprise bubble removal means.
Claim 5
Dependent Claim
54 words
A lithographic projection apparatus according to claim 4, wherein said bubble
removal means comprise a degassing device, said degassing device comprising an isolation
chamber, wherein a space above liquid in said isolation chamber is maintained at a pressure
below atmospheric pressure encouraging previously dissolved gases to come out of
solution and be pumped away.
Claim 6
Dependent Claim
53 words
A lithographic projection apparatus according to claim 4 or 5, wherein said bubble
removal means provides a continuous flow of liquid over the final element of said
projection system and said substrate to transport bubbles in said liquid out of said space
between the final element of said projection system and said substrate.
Claim 7
Dependent Claim
44 words
A lithographic projection apparatus according to any one of the preceding claims,
wherein said bubble reduction means comprise a liquid pressurization device to pressurize
said liquid above atmospheric pressure to minimize the size of bubbles and encourage
bubble-forming gases to dissolve into said liquid.
Claim 8
Dependent Claim
28 words
A lithographic projection apparatus according to any one of the preceding claims,
wherein the composition of said liquid is chosen to have a lower surface tension than
water.
Claim 9
Dependent Claim
38 words
A lithographic projection apparatus according to any one of the preceding claims,
wherein said bubble reduction means treat said liquid before it is supplied to said space
between the final element of said projection system and said substrate.
Claim 10
Dependent Claim
42 words
A lithographic projection apparatus according to claim 9, wherein the treated
liquid is kept in a sealed container, excess space in said sealed container being filled with
one or more of the following: nitrogen gas, argon gas, helium gas or a vacuum.
Claim 11
Dependent Claim
47 words
A lithographic projection apparatus according to claim 2 or 3, wherein an
ultrasonic transducer is arranged in a pulse-echo configuration, said transducer acting both
to transmit ultrasonic waves and, after reflection, to receive ultrasonic waves that have
been attenuated during propagation along a path through said liquid.
Claim 12
Dependent Claim
51 words
A lithographic projection apparatus according to claim 2 or 3, wherein said bubble
detection means comprise two spatially separated ultrasonic transducers, the first arranged
to transmit ultrasonic waves, and the second to receive ultrasonic waves that have been
attenuated during propagation along a path through said liquid between the two
transducers.
Claim 13
Dependent Claim
71 words
A lithographic projection apparatus according to claim 4, 5 or 6, wherein said
bubble removal means includes two spatially separated ultrasonic transducers, arranged to
produce ultrasonic standing-wave patterns within said liquid which trap bubbles within the
nodal regions, said bubble removal means being arranged to displace said bubbles through
the use of phase-adjusting means linked with said transducers, said phase-adjusting means
causing spatial shift of nodal regions and bubbles trapped therein.
Claim 14
Dependent Claim
42 words
A lithographic projection apparatus according to claim 4, 5, 6 or 13, wherein said
bubble removal means comprises an electric field generator for applying an electric field to
said liquid, said electric field being capable of dislodging bubbles attached to said
substrate.
Claim 15
Dependent Claim
36 words
A lithographic projection apparatus according to claim 4, 5, 6, 13 or 14, wherein
said bubble removal means comprises a selective heater for selectively controlling the
temperature and therefore size of bubbles of a particular composition.
Claim 16
Dependent Claim
16 words
A lithographic projection apparatus according to claim 15, wherein said selective
heater comprises a microwave source.
Claim 17
Dependent Claim
42 words
A lithographic projection apparatus according to claim 4, 5, 6, 13, 14 or 15
wherein said bubble removal means comprises a particle input device for introducing
particles into said liquid, and a particle removal device for removing said particles from
said liquid.
Claim 18
Dependent Claim
22 words
A lithographic projection apparatus according to claim 17, wherein said particles
comprise a surface with characteristics that encourage bubbles to attach thereto.
Claim 19
Dependent Claim
84 words
A lithographic projection apparatus according to any one of the preceding claims,
wherein said bubble detection means comprises a light source, a light detector and a light
comparator, said light source and said light detector being arranged so that light emitted by
said source propagates between said source and said detector through a portion of said
liquid, said comparator being arranged to detect changes in the proportion of said emitted
light that arrives at said detector after propagation through a portion of said liquid.
Claim 20
Dependent Claim
177 words
A lithographic projection apparatus comprising: a radiation system arranged to provide a radiation beam; a support structure configured to support a patterning device, the patterning device
being capable of imparting the radiation beam with a pattern in its cross-section,
thus providing a patterned radiation beam; a substrate table configured to hold a substrate; a projection system arranged to project the patterned radiation beam onto a target
portion of the substrate; and a liquid supply system configured to at least partly fill a space between a final
element of said projection system and said substrate with liquid; characterized by further
comprising: a detection system arranged to detect impurities in said liquid, including a light
source, a light detector and a light comparator, said light source and said light detector
being arranged so that light emitted by said source propagates between said source and said
detector through a portion of said liquid, said comparator being arranged to detect changes
in the proportion of said emitted light that arrives at said detector after propagation through
a portion of said liquid.
Claim 21
Dependent Claim
31 words
A lithographic projection apparatus according to claim 20, wherein said detection
system is arranged to detect particles in said liquid between said final element of the
projection system and said substrate.
Claim 22
Independent Claim
110 words
A device manufacturing method comprising the steps of: providing a substrate that is at least partially covered by a layer of radiation-sensitive
material; providing a radiation beam using an illumination system; using a patterning device to impart the radiation beam with a pattern in its cross-section,
thus providing a patterned radiation beam; projecting the patterned radiation beam onto a target portion of the layer of
radiation-sensitive material; and providing a liquid supply system configured to at least partly fill a space between
the final element of said projection system and said substrate with liquid; characterized by further comprising the step of: detecting and reducing bubbles in said liquid supply system.
Claim 23
Dependent Claim
158 words
A lithographic projection apparatus comprising: an illumination system arranged to provide a radiation beam; a support structure configured to support a patterning device, the patterning device
being capable of imparting the radiation beam with a pattern in its cross-section,
thus providing a patterned radiation beam; a substrate table configured to hold a substrate; a projection system arranged to project the patterned radiation beam onto a target
portion of the substrate; and a liquid supply system arranged to at least partly fill a space between a final
element of said projection system and said substrate with liquid; characterized by further
comprising: a liquid quality monitor capable of switching the operational state of the
projection apparatus between an active state and a suspended state, said active state being
selected when the liquid quality is determined to be above a predefined threshold and said
suspended state being selected when the liquid quality is determined to be below a
predefined threshold state.
References Cited (Backward Citations)
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